The present invention relates to the field of roof coverings, in particular to a disposable roof covering comprising a plastic substrate having a porous top surface, and a superabsorbent polymer. The polymer absorbs water contacting the roof covering, e.g., from rainfall or applied using a sprinkler or garden hose, and slowly releases moisture to evaporation to cool the roof and building.
Many advances have been made in roofing and insulation technology to maintain a comfortable temperature inside buildings. These include developments in materials placed in the attic space, such as slurried or rolled insulation. There have been relatively few developments in materials applied to the external surface of roofs. As costs for energy increase, there is an increasing demand for low cost, energy efficient methods to cool buildings.
To address these concerns, materials have been placed over existing roofing materials for added thermal insulation. For example, a covering of vegetation on a roof structure provides a layer of insulation that helps keep the building interior cool in the summer and warm in the winter. Such methods typically use a layer of soil and a complex system of multi-layered materials to protect the underlying structure from damage. This type of construction can be expensive, and may require significant modifications to support and protect the roof structure. Because of the high costs and undesirable weight additions of such systems, many existing buildings cannot utilize these systems.
U.S. Pat. No. 6,606,823, McDonough et al., issued Aug. 19, 2003, discloses a modular roof covering made up of interlocking trays having a component or medium in the tray to absorb moisture and allow it to evaporate or otherwise dissipate over time. The modular roof covering may have vegetation growing in the tray. Other roof coverings merely have water absorption and dissipation capability, while other coverings have photovoltaic cells for the collection and use of solar energy.
U.S. patent application 2003/0065296, Kaiser et al., published Apr. 3, 2003, discloses an absorbent material containing at least about 30% superabsorbent polymer, a thermoplastic polymer binder resin, and from about 0.1% to 10% water. The method of making the absorbent material includes combining binder resin and absorbent polymer in a twin-screw extrusion mechanism, and compounding and extruding the composition through the exit openings. The quenched or non-quenched extrudate may be made in the form of a pellet, film, or fibrous strand.
Despite these advances in the art, there is a continuing need for a low cost, lightweight disposable roof covering for cooling buildings while at the same time reducing energy usage and environmental impact.